Process for preparing dextrose containing syrups

ABSTRACT

The invention is directed to a process for preparing dextrose containing syrups having a predictable dextrose content. During enzymatic hydrolysis of starch to dextrose, C1O2 is incorporated into the hydrolysate to inactivate the enzyme when the dextrose content of the hydrolysate reaches a predetermined level.

llnlted States Patent Robert G. Dworschack;

Carolyn A. Nelson, both of Clinton, Iowa 765,642

Oct. 7, 1968 Dec. 28, 1971 Standard Brands Incorporated New York, N.Y.

[72] Inventors [211 App]. No. [22] Filed [45] Patented [73] Assignee [54] PROCESS FOR PREPARING DEXTROSE CONTAINING SYRUPS 10 Claims, No Drawings [52] U.S. Cl 195/31 [51] Int. Cl C121) 1/00 [50] Field ofSearch 195/31,

[56] References Cited UNITED STATES PATENTS 3,137,639 6/1964 Hurst et a]. 195/31 3,149,049 9/1964 Walkup et a1 195/31 3,513,072 5/1970 Frankevicz et a1 195/31 OTHER REFERENCES Cravens, Tappi, p. 53A- 55A, V01. 49, No. 8, 1966. Primary Examiner-A. Louis Monacell Assistant Examiner-Gary M. Nath Attorney-- Aaron B. Karas PROCESS FOR PREPARING DEXTROSE CONTAINING SYRUPS THE INVENTION The present invention relates to a process for preparing dextrose containing syrups. More particularly, the present invention relates to a method of producing dextrose containing syrups having a substantially predictable dextrose content.

The major use of dextrose containing syrups is in food processing, for instance in the baking, beverage, cannery and confectionery industries, to provide sweetness, body, to regulate crystal growth, etc. The specific types of dextrose containing syrup used by these industries depends, of course. upon the properties desired in the foods which they produce. For instance, when it is desired to provide body to a food, generally, a dextrose containing syrup will be used which contains relatively large amounts of dextrins. The baking industry, on the other hand, is desirous of obtaining dextrose containing syrups having large amounts of dextrose present so that the fermentability of the syrup dry substance is high. In the use of such syrups it is important that they be noncrystallizing in order that they can be pumped and otherwise handled in a manner nonnal to the industry. Maltose is sometimes provided in the syrups along with dextrose in order to increase the fermentability of the dry substance while still providing noncrystallizing syrups. The maximum amount of dextrose which may be present in syrups is limited by its solubility. ln syrups having a dextrose content of above about 45 percent some of the dextrose will crystallize out of solution under normal conditions.

Dextrose containing syrups are produced by hydrolyzing starch. The components of starch hydrolysates may generally be grouped into five categories. These are dextrose, a monosaccharide; maltose, a disaccharide; trisaccharides; oligosaccharides and dextrins. The chemical and physical properties of dextrose containing syrups, and of course the use to which these syrups are put, are primarily dependent upon their content of the five principal components. The amounts of the five principal components may be varied widely and is principally dependent upon the method and extent of hydrolysis of the starch.

Methods of producing dextrose containing syrups are well known in the art. Two methods disclosed in the art are acidenzyme and enzyme-enzyme processes. In the acid-enzyme conversion process, starch is first partially hydrolyzed or liquefied, for instance, by forming an aqueous suspension containing about 35 to 40 percent starch and incorporating therein an acid such as hydrochloric. The suspension is then heated to high temperatures thereby partially hydrolyzing the starch. The suspension may be cooled and treated with a gluoamylase preparation at a suitable concentration and pH range to enzymatically convert the partially hydrolyzed starch to dextrose. The acid-enzyme process is disclosed, for instance, in US. Pat. Nos. 2,305,168; 2,53l,999; 2,893,921; and 3,042,584.

Alphaand beta-amylases derived, for example, from malted cereal grains may be added to the partially acid hydrolyzed starch along with glucoamylase to enzymatically convert a portion of the starch to maltose when it is desired to produce dextrose containing syrups having present substantial amounts of maltose.

In the enzyme-enzyme conversion process, generally, a starch slurry is formed and a starch liquefying enzyme, for instance bacterial alpha-amylase, added, and the starch slurry heated to partially hydrolyze the starch. The partial hydrolysis is generally carried out at a temperature in the range of 80 to 90 C. The DE of the slurry after the partial hydrolysis may be in the range of from to 20.

Any suitable starch liquefying enzyme may be used to partially hydrolyze the starch. Exemplary of such hydrolyzing enzymes are those produced by the members of the Bacillus .rubtilis species, Aspergillus niger and other species of the Aspergillus genus and by malted cereal grains.

The partially hydrolyzed starch slurry or liquefied starch may be treated with a glucoamylase preparation to convert the starch to dextrose. When it is desired, the partially hydrolyzed starch slurry may first be treated with alphaand betaamylases from sources such as malted cereal grains to convert the starch to maltose and then this hydrolysate may be treated with a glucoamylase preparation to convert a minor or major portion of the maltose to dextrose.

The enzymatically converted hydrolysates are subjected to various refining procedures well known in the art to remove colored bodies,-odoriferous materials and constituents which contribute to the ash content of the syrup.

In the art, the term hydrolysates" usually connotes unrefined dextrose containing syrups whereas after refining the dextrose containing syrups are termed "syrups".

in commercial practice, it may sometime take 8 to 24 hours or longer, depending upon the refining conditions and the physical setup of the equipment used, to completely refine a starch hydrolysate. During this period of time, the hydrolyzing enzyme, for instance glucoamylase, present in the hydrolysates will continue to hydrolyze the polysaccharide materials therein thereby increasing the dextrose content of the same. Because of this, it is difiicult to produce dextrose containing syrups having present predictable quantities of dextrose. This problem has been overcome in the past by lowering the pH of the hydrolysate and/or raising the temperature thereof to inactivate the enzymes. These methods are not entirely satisfactory since, for instance, lowering the pH of the hydrolysate will contribute to the ash content of the hydrolysate when it is subsequently neutralized with an alkali and high temperatures tend to cause further color development.

lt is the principal object of the present invention to provide an enzymatic method for producing dextrose containing syrups having a substantially predictable dextrose content.

This object and other objects of the present invention, which will be apparent from the following description, may be attained by liquefying starch, incorporating into the liquefied starch a dextrose forming enzyme, subjecting the liquefied starch containing the dextrose forming enzyme to starch hydrolyzing conditions to provide a hydrolysate containing a substantially predictable dextrose content, treating the hydrolysate with a sufficient amount of C10 to substantially inactivate the dextrose forming enzyme and refining the treated hydrolysate to provide a dextrose containing syrup. The term starch" as used herein includes all raw starches such as corn, tapioca, wheat, arrowroot, rice and the like.

The amount of chlorine dioxide necessary to substantially inactivate the dextrose forming enzymes is dependent upon many factors, such as the exact process used to prepare the hydrolysate, the temperature, the pH, the amount of proteinaceous materials present, and the type and amount of enzyme used. At relatively high temperatures and outside the pH range in which optimum enzyme activity occurs, lesser amounts of chlorine dioxide are required than at lower temperatures and at a pH range within which optimum enzyme activity occurs. in order to inactivate glucoamylase produced by Aspergillus niger, it is preferred that the temperature of the hydrolysate be within a range of from about 40 to about 70 C. and most preferably be within a range of about 50 to about 60 C. The pH of the hydrolysate during inactivation of the glucoamylase may be in the range of from about 2.5 to about 4.5 and preferably at about 3. Generally within the preferred pH and temperature ranges from about to about ppm, chlorine dioxide based on the weight of the dry substance present in the hydrolysate will substantially inactivate the glucoamylase.

The chlorine dioxide may be provided in the hydrolysate by introducing gaseous C10 a water solution of C10 a salt of chlorous acid or a combination of sodium chlorite and a peroxygen compound such as hydrogen peroxide, sodium peroxide and sodium percarbonate.

ln a preferred embodiment of the present invention, liquefied starch is enzymatically converted to a high fermentablc hydrolysate, for instance having a dextrose content of from about 40 to about 45 percent and a maltose content of from about 40 to about 45 percent. This enzymatic conversion may be accomplished by first treating a starch slurry with a starch liquefying enzyme and then with enzymes which produce maltose, for instance by the addition of distillers barley malt, to obtain a high content of maltose, generally in the range of from about 50 to about 65 percent. Then a glucoamylase preparation, such as one derived from Aspergillus niger, is added and conversion allowed to proceed until a predetermined amount of dextrose is formed in the hydrolysate. C is then provided in the hydrolysate in order to inactivate the enzymes. Typically, the C10 is provided in the hydrolysate when a level of from about 40 to about 45 percent dextrose and from about 40 to about 45 percent maltose is reached. Preferably, the glucoamylase should be inactivated when the dextrose content of the hydrolysate reaches a level of from about 43 to about 45 percent. These hydrolysates may be filtered, refined and concentrated to obtain high fermentable syrups. As discussed previously, high fermentable syrups find particular application in the baking industry. The most desirable syrups for the baking industry from the standpoint of handling are those having a maximum dextrose content at or below that at which dextrose will crystallize out of solution.

In order to more clearly describe the nature of the present invention, specific examples will hereinafter be described. it should be understood, however, that this is done solely by way of example and is intended to neither delineate the scope of the invention nor limit the ambit of the appended claims. In the examples and throughout the specification, percentages refer to percent by weight and are based upon the dry substance present unless otherwise specified.

The analytical procedures and testing methods referred to in this specification were performed by the following procedures:

Determination of Glucoamylase Activity Exactly 25 g. of soluble starch (Merck Lintner StarchSpecial for Diastatic Power Determination) was heated, with stirring, in 700 ml. of distilled water until boiling and then held at this temperature for 5 minutes. The starch preparation was cooled to ambient temperature with constant stirring, the pH adjusted to 4310.1 with 20 ml. of a 1.0 molar solution of sodium acetate, (pH adjusted to 4.3 with acetic acid) and diluted to 1000 ml. with distilled water. Then 100 ml. of this starch substrate was pipetted into a 250 ml. Erlenmeyer flask, stoppered and attempered at 60 C. for minutes in a constant temperature water bath. The enzyme preparation was diluted by transferring 50 ml. of the preparation to a 2000-ml. volumetric flask and making up to volume. A 3-ml. aliquot of the diluted enzyme solution was added to the starch substrate, mixed thoroughly, stoppered, and held in a water bath maintained at 60 C. for exactly 1 hour. At the end of 1 hour, 5 ml. of a 5 percent sodium hydroxide solution was added to the flask to terminate the enzyme action. The enzymatically converted hydrolysate was cooled to about 30 C.

Ten ml. of the hydrolysate was pipetted into a Fehlings titration flask containing 25 ml. of boiling Fehlings solution. The titration with standard dextrose solution was completed using methylene blue as an indicator. A blank determination using 3 ml. of distilled water in place of the enzyme preparation was performed in the manner described above. The activity was calculated as follows:

- Glucoamylase un1ts/g. (F) where:

B. ml. of standard dextrose solution required for the control.

D ml. of standard dextrose solution required for the enzymatically converted hydrolysate,

S g. of dextrose per ml. of standard dextrose solution T final volume of enzymatically converted hydrolysate E volume, ml. of diluted enzyme solution (2000-except with enzyme preparation of 0 to 3 potency in which the final dilution is I000 ml.)

F volume, ml. of enzymatically converted hydrolysate titrated with Fehlings solution l0).

G= reaction time in hours l H volume, ml. of diluted enzyme solution added to the substrate-buffer solution (3).

W= weight in g. of enzyme preparation used.

Determination of the Composition of the Syrups The composition of the syrups described herein were determined according to the chromatographic procedures described by L. D. Ough in Methods in Carbohydrate Chemistry, 4, pp. 91-98 (1964), Academic Press, New York.

Definition of Dextrose Equivalent The abbreviation, DE, contained herein refers to dextrose equivalent and is defined as the reducing sugars expressed as dextrose and calculated as a percentage of the dry substance. The analysis was performed according to Method E-26 in the Standard Analytical Methods of the Member Companies of the Corn industries Research Foundation.

EXAMPLE I This example illustrates the use of various amounts of C10 to substantially inactivate glucoamylase in cornstarch hydrolysates having various pH's.

A slurry of cornstarch (about 29.6 percent dry substance) was liquefied with Bacillus subtilis alpha-amylase at 88 C. and at a pH 6.8 to 7.0. The liquefied starch slurry was autoclaved, the temperature of the slurry lowered to 55 C. and the pH adjusted to 5.7. One percent ground distillers malt was added to the slurry, and hydrolysis carried out for 21 hours. A glucoamylase preparation produced by a culture of Aspergillus awamorii was then added at a level of 3 glucoamylase units per 100 g. of substrate dry basis. The temperature was maintained at 55 C. for an additional 48 hours at which time the DE was 66.3 and the pH was 4.4.

The hydrolysate was divided into three 400 ml. portions. The pH of two of the portions was adjusted with a dilute H solution to 3.0 and 3.5, respectively. The pH of the third portion was not adjusted. Each of the three portions was next divided into 4 portions of ml. One of the 100 ml. portions at each pH level served as a control. lnto each of the other portions were introduced various amounts of C10 shown in table I below. After the introduction of the C10 the hydrolysates were placed in a 55 C. water bath for 24 hours and the DE determined. The DEs are shown in table I.

TABLE I ClOz h I N 60 300 p y to one p.p.m. p.p.m. p. .m. ysate (DE) (DE) (DE) (DE) From the above table, it is apparent that as the amount of C10,, introduced was increased the glucoamylase was inactivated to a greater degree.

EXAMPLE ll This example illustrates that certain agents which are generally considered to be enzyme inactivators do not substantially inactivate glucoamylase.

6 An acidified cornstarch slurry containing about 35 percent TABLE IV dry substance was converted under 40 p.s.i.g. steam pressure until the DE of the slurry reached 48. The pH of the converted liquor was adjusted to 4.6 with Na CO The insoluble materi- PPM Cw als were removed by skimming and filtration. The filtrate was 5 2 concentrated under vacuum to about 55 percent solids. The None 200 500 temperature of the filtrate was adjusted to 55 C., the pH adjusted to 5 with a dilute solution of NaOH and 0.35 percent DE DE DE Dextrinase A (marketed by Miles Chemical Co.) was added. pH DE 1. DE 1mmSc mg 1mm. The filtrate was hydrolyzed at 55 C. for 47 hours. This hydrolysate which had a DE of 68 was divided into portions 2 585 5 M 59 M and 5 portrons treated with the agents shown below in table ll. 3 01.9 2.9 59.4 0.4 59.2 0.2 The remaining portion served as a control. These portions 4 3-1 61-2 2.2 59.4 0.4 were maintained at 55 C. for 91 hours, and the DE of the por- 5 M tions determined. Another hydrolysate was prepared in the 6 same manner as described above except that it was maintained at 55 C. for 45 hours and the DE thereof was 70.8. This was divided into 4 portions and into 3 of the portions were added From the f table seen that generally as the P P various amounts f H202 The remaining portion Served as a the hydrolysate is lowered the C10 becomes more effectwe 1n control. These were maintained at 55 C. for 90 hours and the macuvatmg the glucoamylase- DE of the portions determined. The results of this experiment are shown in tables 11 and 111. EXAMPLE W This example illustrates the inactivation of glucoamylase in a cornstarch hydrolysate by in situ generation of C10 from TABLE II Naclor An enzyme liquefied cornstarch slurry was prepared in the DE an" DE an DE manner described in example I. One percent ground distillers Age, p" 47 hours hum Increase malt and 3 glucoamylase units per 100 g. dry substance were added. The liquor was maintained at 55 C. and at a pH of 5.4 Comm 5,0 680 785 ms for 22 hours. The resulting hydrolysate had a DE of 50.2 and 1.0% Sarkosyl' 5.0 68.0 79.6 IL6 was divided into 4 portions. The portions were treated in the 32:52:82? :8 2:3 23-; g; manner shown in table V and maintained at 55 C. for 47.5 A'djusmd g hours. The DE of the portions was determined after 23.5 Adjusted with mm. 3.0 68.0 110.0 12.0 hours and after 47.5 hours. The results of this experiment are shown below in table V.

"Nacyl sarcosine surfactant, Geigy Industrial Chemicals.

TABLE V TABLE lll 40 23.5 hours 47.5 hours After After DE DE DE Treatment Treatment Agent pH hours l35 hours Increase 45 Control 5.0 10.0 13.4 7.6 Tmam'em DE DE Db 0.013% 11,0 5.0 10.1; 11.1; 1.0 0.0 1 70.8 7715 Control, pH 4.5 50.2 59.9 68.2 005% 1 Control, pH 3.0 50.2 58.4 04.3

50 1 with HCI 0.1% Nac10,, 11 3.0 50.2 50.8 50.8 From tables [I and Ill, it is apparent that certain agents 5L9 which are generally considered to be enzyme inactivators have no appreciable effect on Dextrinase A, a dextrose forming enzyme. Large amounts of NaOCl did significantly inactivate The terms and P F f' wh'ch f h BmPIOYefj are Dextrinase A but imparted phenollike odors and tastes to the h as tefms of deschphoh and of f and It hot fi i h d Syrup intended in the use of such terms and expressions to exclude any equivalents of the features shown and described or por' EXAM "I tions thereof, since it is recognized that various modifications This example illustrates the use of C10 to inactivate glu- Y w Scope ofthe mvenuon Clalmed' coamylase in cornstarch hydrolysates at various pH levels and at 0 mm with various amounts ofclozi l. A method of produclng a dextrose contalmng syrup hav- An enzyme liquefied cornstarch slurry was prepared in the P 3 s ubstamlauy predlctabl e 3 i compnsmg manner described in example I. One percent ground distillers lquefymg f mcorporanflg hquefied Starch a man and 3 glucoamylase units per 100 g. of dry substance dextrose formmg enzyme, sub ecting the hquefied starch conwere added. The liquor was maintained at 55 C. and at a pH the dexmse formmg enzyme 9 tarch hydmlyzmg of 5 for three days The resulting hydrolysate had 3 DE f 59 condmons to prov1de a hydrolysate contammg dextrose, treatand was divided into five portions. The pH of the portions was "8 the hydrolysate with a Suh'lcleht hmouht of 2 adjusted to the values shown in table IV. Each of these por- Stahhah) inactivate the dextrose fol'hhhg enzyme thereby tions was divided into 3 parts and to two of the three parts taining a hydrolysate with a predictable dextrose content, and C10 was added in amounts shown in table IV. The other parts refining the treated hydrolysate to provide a dextrose containserved as controls. All the parts of the portions were maini g yr ptained at 55 C. for 12 hours and the DE of each part deter- 2. A method of producing a dextrose containing syrup havmined. The results of this experiment are shown in table lV. ing a substantially predictable dextrose content as defined in 1 claim 1, wherein the starch is enzymatically liquefied.

3. A method of producing a dextrose containing syrup having a substantially predictable dextrose content as defined in claim 2, wherein the dextrose forming enzyme is glucoamylase.

4. A method of producing a dextrose containing syrup having a substantially predictable dextrose content as defined in claim 3, wherein the hydrolysate being treated with C10, is at a temperature in the range of from about 40 to about 70 C.

5. A method of producing a dextrose containing syrup having a substantially predictable dextrose content as defined in claim 4, wherein the hydrolysate being treated with the C10 has a pH in the range offrom about 2.5 to about 4.5.

6. A method of producing a dextrose containing syrup having a substantially predictable dextrose content as defined in claim 5, wherein the amount of C10 used for treating the hydrolysate is from about 60 to about 500 p.p.m. based upon the dry substance present in the hydrolysate.

7. A method of producing a dextrose containing syrup having a substantially predictable dextrose content as defined in claim 6, wherein the glucoamylase incorporated into the liquefied starch is produced from micro-organisms of the Aspergillus genus.

8. A method of producing a dextrose containing syrup having a substantially predictable dextrose content as defined in claim 7, wherein the temperature of the hydrolysate being treated with the C10, is from about 50 to about 60 C. and the amount of C10 used is from about to I50 p.p.m. based upon the dry substance present in the hydrolysate.

9. A method of producing a dextrose containing syrup having a substantially predictable dextrose content as defined in claim 8, wherein the liquefied starch is also treated with a maltose forming enzyme in order to provide a hydrolysate with substantial quantities of maltose.

10. A method of treating a dextrose containing syrup having a substantially predictable dextrose content as defined in claim 8, wherein the hydrolysate is treated with C10 when the hydrolysate contains from about 40 to 45 percent dextrose. 

2. A method of producing a dextrose containing syrup having a substantially predictable dextrose content as defined in claim 1, wherein the starch is enzymatically liquefied.
 3. A method of producing a dextrose containing syrup having a substantially predictable dextrose content as defined in claim 2, wherein the dextrose forming enzyme is glucoamylase.
 4. A method of producing a dextrose containing syrup having a substantially predictable dextrose content as defined in claim 3, wherein the hydrolysate being treated with C102 is at a temperature in the range of from about 40* to about 70* C.
 5. A method of producing a dextrose containing syrup having a substantially predictable dextrose content as defined in claim 4, wherein the hydrolysate being treated with the C102 has a pH in the range of from about 2.5 to about 4.5.
 6. A method of producing a dextrose containing syrup having a substantially predictable dextrose content as defined in claim 5, wherein the amount of C102 used for treating the hydrolysate is from about 60 to about 500 p.p.m. based upon the dry substance present in the hydrolysate.
 7. A method of producing a dextrose containing syrup having a substantially predictable dextrose content as defined in claim 6, wherein the glucoamylase incorporated into the liquefied starch is produced from micro-organisms of the Aspergillus genus.
 8. A method of producing a dextrose containing syrup having a substantially predictable dextrose content as defined in claim 7, wherein the temperature of the hydrolysate being treated with the C102 is from about 50* to about 60* C. and the amount of C102 used is from about 100 to 150 p.p.m. based upon the dry substance present in the hydrolysate.
 9. A method of producing a dextrose containing syrup having a substantially predictable dextrose content as defined in claim 8, wherein the liquefied starch is also treated with a maltose forming enzyme in order to provide a hydrolysate with substantial quantities of maltose.
 10. A method of treating a dextrose containing syrup having a substantially predictable dextrose content as defined in claim 8, wherein the hydrolysate is treated with C102 when the hydrolysaTe contains from about 40 to 45 percent dextrose. 